Microstructure and stress corrosion cracking of a SA508-309L/308L-316L dissimilar metal weld joint in primary pressurized water reactor environment

Lijin Dong^1,2，Cheng Ma¹，Qunjia Peng¹，En-Hou Han¹，Wei Ke¹

1. Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences2. School of Materials and Engineering, Southwest Petroleum University

摘 要：Stress corrosion cracking（SCC） of an SA508-309 L/308 L–316 L dissimilar metal weld joint in primary pressurized water reactor environment was investigated by the interrupted slow strain rate tension tests following a microstructure characterization. The 308 L weld metal shows a higher content of ■ferrite than the 309 L weld metal. In addition, no obvious Cr-depletion but carbides precipitation at■ phase boundaries was observed in both 308 L and 309 L weld metals. The slow strain rate tension tests showed that the SCC susceptibility of the base and weld metals of the dissimilar metal weld joint follows the order of SA508 < 308 L weld metal < the heat affected zone of 316 L base metal < 309 L weld metal.The higher SCC susceptibility of 309 L weld metal than that of 308 L weld metal is likely due to the lower content of ■ferrite. In addition, a preferential SCC initiation in the 309 L weld metal adjacent to 308 L weld metal is attributed to few carbides in this region.

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